Rotating machines, such as centrifugal compressors, include impellers provided inside a casing so as to be rotatable relative to the casing. A fluid sucked from the outside of the casing is discharged to a radial outer side of a flow passage within each impeller by rotating the impellers to raise the pressure. In the centrifugal compressors, the shape of each blade provided in the impeller is optimized in order to improve performance.
A technique regarding the shape of such a blade is disclosed in, for example, PTL 1. In a centrifugal compressor of PTL 1, the distribution of the blade angle of the blade is specified in consideration of the flow passage area between blades.